Ravignani, A. 1, 2 & Sonnweber, R. 1
1 Department of Cognitive Biology, University of Vienna
2 Artificial Intelligence Lab, Vrije Universiteit Brussel
Humans and other animals are constantly exposed to environmental stimuli, from which they extract sensory regularities. Moreover, they often relate and integrate one-dimensional quantities across sensory modalities, for instance relating conspecific faces to voices. If basic patterns like repetitions and identities are perceived in different sensory modalities, it could be advantageous to detect cross-modal isomorphisms, i.e. modality-independent representations of structural features, which could be used in visual, tactile, and auditory processing. Humans can transfer structural regularities learnt in one modality (e.g. visual sequences) to another modality (e.g. unfamiliar sound sequences). To date, this ability to map regularities across domains has not been demonstrated in other animals. Here we show that two chimpanzees trained to respond to visual sequences spontaneously generalized the structural rule across modalities: previously unheard sound sequences influenced the choice of visual sequences solely based on structural similarities (Ravignani, Sonnweber & Fitch, in prep.). Crucially, chimpanzees had never been trained to associate sounds with images. We provide the first evidence of structure learning across modalities in a non-human animal. Cross-modal abstraction capacities transcend linguistic abilities, and might involve evolutionary old neural mechanisms.